This research is concerned with the elucidation of the mechanism of energy conversion in photsynthetic systems; algal, bacterial and green plant. In green plant and algal photosynthesis, the reduction of NADP is coupled to the esterification of ADP and Pi. The resultant products, NADPH and ATP, are necessary for the fixation of carbon dioxide into cellular material. We will continue our studies on the identification and nature of the cofactors involved in the pathway of electron flow leading to NADPH formation. In support of the biochemical approach, we have recently initiated a collaborative program (with Dr. R.K. Togasaki of this department) of mutational analysis using the green alga, Chlamydomonas reinhardi. We have available now numerous mutants which we are attempting to categorize with respect to the imposed lesion; photosystem I mutants, photosystem II mutants, carbon metabolism mutants, photophosphorylation mutants, and mutants deficient in the pathway interconnecting the two photosystems.